ESL's are funky, it's a totally different ballgame when looking for amps.
I think 48VRMS would do the trick.
Still it'd be nice to hear what Bruno thinks.

What trick? You normally need a couple of thousand volts to drive an ESL; step up transformers with a 1:150 ratio are not uncommon as part of the ESL.
With less amp output voltage you would need a bigger step up to get the same voltage (ignoring other issues like capacities for the moment...).

Bruno already answered the ESL question somewhere. IIRC there is absolutely no problem as long as you stay below clipping. Due to the interaction of the amp and the reactive load clipping can sound very nasty but you would have to search for the complete answer.

Other Class D amps may have big problems with ESLs, as their max output current at high frequencies is very limted, and ESL typically have very low impedance at high frequencies. Also - the high frequency response of some class D amps is dependant on the load impedance.

Typically, class D amps have not been the best choice for driving electrostatic loudspeakers (as opposed to something like planar magnetics, which rock with class D). But nCore is new, and appears to solve many of the reactive output impedance issues of some class D amps. I think it would be best to seek an answer from Bruno and/or Hypex directly to determine how well an nCore would work with a given ESL. I think a complete impedance curve for the speaker would be good to have them take a look at.

I couldn't agree more about Class D and planar magnetics. My ACOUSTICIMAGERY D400M Monos (using UcD400HG+HxR and SMPS400A400) have discovered a 'soulmate' in the Eminent Technology LFT-8B's. The synergy between these magical planars and the Hypex amps is just wonderful.
I can only believe that the N Core modules will sound even more amazing. I'll just have to wait until there are more available.

The NC1200 has been tried on a few electrostatics (ESL63 and Final), to very good effect (except that the owner of the Final overestimated the power handling capability of the speaker and burned a hole in the diaphragm during a loud passage). UcD does quite well too.

Conceptually class D and electrostatics are made for eachother. Since ESL's are almost entirely reactive, no net power is drawn. It just circulates round between the storage caps and the speaker. Actual power efficiency must be enormous. But indeed, most class D amps lack global feedback and you really need that to keep the frequency response flat.

Done tonight, online probably tomorrow morning. The bit I'm still working on are the installation instructions, wiring mainly. I've noticed that differential inputs (and what benefits they have over single-ended) still elude some people, so I'm trying to write a reliable guide.